Abstract
The \(M_w=7.6\) earthquake, known as Centenary Earthquake, occurred in the Scotia Sea region near the South Orkney Islands, Laurie Island, where is located the permanent Argentinean Antarctic Base Orcadas, here from 1997 operates a seismographic station ORCD, which has recorded several thousands of aftershocks, the most energetic ones recorded by all the instruments of the Antarctic Seismographic Argentinean-Italian Network (ASAIN). The aftershocks data available at ORCD station, till 60 days following the main shock were compiled. The plot of aftershocks rate with time was found to be oscillatory decay. Then, we inverted regional waveforms from ASAIN and International Federation of Digital Seismograph Networks (FSDN) stations to determine source parameters and source time functions for a set of aftershocks with magnitudes in the range 4.3–5.6 \(m_b\). For the regional inversion we applied a methodology for the determination of the seismic moment tensor by means of full waveform inversion. The results obtained reflect the normal character of the main system fault, characterizing the study area.
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Acknowledgements
The project “Broad Band seismology in the Scotia Sea Region” is financially supported by the Italian Programma Nazionale di Ricerche in Antartide in the framework of the PNRA research area “Geodesia e Osservatori”. Thanks are due to the Argentinean institutions cooperating to the ASAIN: Dirección Nacional del Antártico–Instituto Antártico Argentino. We are also extremely grateful to the military and civilian personnel operating in the Argentinean Bases Esperanza, Jubany (Now Carlini), Orcadas, San Martín, Belgrano II and Marambio for their help in maintaining the field installations and in the seismographic stations operation. We also thank the Abdus Salam International Centre for Theoretical Physics (ICTP) and the OGS for financing Milton P. Plasencia Linares’s TRIL fellowship. Thanks are due to M. Busetti for her help in the geological interpretation of the results.
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Plasencia Linares, M.P., Guidarelli, M., Russi, M., Panza, G.F. (2018). Investigating the Focal Mechanisms of the August 4th, 2003, \(M_{w}\) 7.6, South Orkney Islands Earthquake and its Aftershocks Sequence. In: D'Amico, S. (eds) Moment Tensor Solutions. Springer Natural Hazards. Springer, Cham. https://doi.org/10.1007/978-3-319-77359-9_17
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